New study: Patients on even low levels of warfarin may not be good candidates for tPA

Patients already taking the blood thinner Coumadin (warfarin), even at low doses, may not be good candidates for the clot-busting drug tPA in the event of a stroke, a new study indicates.

Thrombolysis (treatment with the “clot-busting” drug tPA) in the early stages of a new stroke is often the very best hope a patient has to recover with minimal brain damage. It’s been called a ‘miracle drug,’ because many patients recover with minimal or no loss of function. But tPA comes with a risk: the potential for bleeding inside the brain, which can often be more catastrophic than the stroke.

For that reason, there are strict protocols indicating when tPA should be considered. It must be given within three hours of the onset of symptoms and should not be given to patients for whom the risk of bleeding outweighs the benefits. It’s a long list: patients who’ve had seizures, head trauma, major surgery, who’ve been given the blood thinner heparin.  Patients taking Coumadin (warfarin) have also been excluded if their INR (a measure of how “thin” their blood is compared to a “normal”) is significantly higher than normal.

A “normal” INR is about 1.0. The “therapeutic range” to help prevent blood clots is usually between 2.0 and 3.0.  Patients taking warfarin at below-therapeutic levels (with an INR below about 1.7) have been considered eligible for thrombolysis.

The current study, conducted by the Medical University Innsbruck, Innsbruck, Austria, found that patients taking warfarin at subtherapeutic levels had a significantly higher rate of symptomatic intracranial hemorrhage than other patients.

The study was small, but it included a “meta analysis” of nine past studies. Four of them found a significantly increased bleeding risk among patients with elevated but “subtherapeutic” INR. Five found no increased risk.

So the jury is still out. An editorial in the Journal Neurology summed up our current state of knowledge: “But as the overall findings support the possibility of an increased bleeding risk in patients with warfarin … “clearly, the decision for [intravenous] thrombolysis needs to be taken with caution in these patients.”

For those of us who take Coumadin, it sometimes seems like we’re tip-toeing everyday through a minefield of potentially fatal risks and decisions. Some days I want to stick my head in the sand, ignore the risks and just live my life.  Not smart. The risks are real, and the day may come when we or our families have to face hard decisions like this. That’s why we need to stay informed.  Thanks to Tina Pohlman for sharing this item on the APSFA Facebook site.

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